Cancelling of COS from one employer and filing from other

[mnvsriram]

Hi forum members,
I really need your help. Please advise.

I am talking to two employers(A and B). Cleared interview rounds with A and have a offer in hand and the interviews are in process with B which may take around a month time to complete all the rounds of the interview.

Employer B is better than employer A in terms of job security and salary. Employer A is saying he will file for the COS immediately and he don't want to delay as the requirement is urgent. I don't want to miss the opportunity with Employer A as I am not sure if I will get the offer from Employer B. But, in case if I get a offer from employer B, I would like to go with employer B.

If I say yes to employer A to file for the COS and if I get the COS from employer A, can I cancel the same in case if I get an offer from employer B?

To make it clear, if I get COS from one employer and before actually going for visa office for stamping, can I ask the employer to cancel the COS and can I proceed with other employer?

Please advise. Request you to please point to any document/link which has any related information to my query.

Employer A is considering to file Tier 2 general visa and I am not sure what type of visa will employer B choose to apply.

Thanks a lot in advance.

- RK